Hilo

Today: Partly sunny with scattered showers. Highs 74 to 80 near the shore to 60 to 67 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers early in the evening, then showers likely in the late evening and early morning. Occasional showers early in the morning. Lows 60 to 69 near the shore to 50 to 56 at 4000 feet. North winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 80 percent.

Tuesday: Cloudy. Occasional showers early in the morning, then scattered showers in the late morning and afternoon. Highs 75 to 81 near the shore to 63 to 68 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 80 percent.

Kona

Today: Mostly sunny in the morning, then cloudy with scattered showers in the afternoon. Highs 80 to 85 near the shore to around 64 near 5000 feet. Light winds. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers early in the evening. Lows 67 to 72 near the shore to 46 to 53 near 5000 feet. Light winds. Chance of rain 40 percent.

Tuesday: Mostly sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 80 to 85 near the shore to around 65 near 5000 feet. Northeast winds around 10 mph shifting to the west in the afternoon. Chance of rain 20 percent.

Waimea

Today: Breezy. Partly sunny with scattered showers. Highs 60 to 83. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 59 to 64 near the shore to 51 to 60 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tuesday: Breezy. Mostly cloudy with scattered showers. Highs 63 to 83. East winds 10 to 20 mph. Chance of rain 50 percent.

Kohala

Today: Breezy. Partly sunny with scattered showers. Highs 60 to 83. Northeast winds 10 to 20 mph. Chance of rain 50 percent.

Tonight: Breezy. Mostly cloudy with scattered showers. Lows 59 to 64 near the shore to 51 to 60 near 3000 feet. East winds 10 to 25 mph. Chance of rain 50 percent.

Tuesday: Breezy. Mostly cloudy with scattered showers. Highs 63 to 83. East winds 10 to 20 mph. Chance of rain 50 percent.

South Big Island

Today: Mostly sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 81 near the shore to around 64 near 5000 feet. Southeast winds up to 15 mph. Chance of rain 40 percent.

Tonight: Mostly cloudy. Scattered showers early in the evening. Lows around 69 near the shore to around 50 near 5000 feet. Northeast winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 40 percent.

Tuesday: Mostly sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs around 81 near the shore to around 65 near 5000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.

Puna

Today: Partly sunny with scattered showers. Highs 74 to 80 near the shore to 60 to 67 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Tonight: Mostly cloudy. Scattered showers early in the evening, then showers likely in the late evening and early morning. Occasional showers early in the morning. Lows 60 to 69 near the shore to 50 to 56 at 4000 feet. North winds up to 15 mph increasing to 10 to 15 mph after midnight. Chance of rain 80 percent.

Tuesday: Cloudy. Occasional showers early in the morning, then scattered showers in the late morning and afternoon. Highs 75 to 81 near the shore to 63 to 68 at 4000 feet. Northeast winds 10 to 15 mph. Chance of rain 80 percent.

Waikoloa

Today: Breezy. Mostly sunny in the morning, then mostly cloudy with isolated showers in the afternoon. Highs 77 to 86 near the shore to 63 to 69 above 4000 feet. Northeast winds up to 25 mph. Chance of rain 20 percent.

Tonight: Mostly cloudy. Breezy. Isolated showers in the evening. Lows 65 to 72 near the shore to 47 to 53 above 4000 feet. East winds up to 25 mph becoming 10 to 20 mph after midnight. Chance of rain 20 percent.

Tuesday: Mostly sunny. Highs 78 to 86 near the shore to 64 to 70 above 4000 feet. Northeast winds 10 to 15 mph.

Detailed Forecast

Synopsis

Locally breezy trades will prevail into next weekend, occasionally delivering low clouds and showers that will primarily dampen windward areas. A nearby trough aloft will bring periods of high clouds through the week, initially over Maui County and the Big Island, then thickening over all islands Thursday and Friday.

Discussion

A surface ridge N of the islands will support locally breezy trade winds into next weekend. Weak low-level convergence will support low cloud and shower formation along dissipated frontal boundaries at times over the next couple of days, with this moisture primarily affecting windward areas. For today, limited upstream and increased atmospheric stability will lead to just a few windward showers into this afternoon, with the bulk of the showers over windward Big Island. Model guidance indicates that increased low-level moisture seen on satellite about 200 to 500 miles NE of the islands will arrive by this evening. This moisture will mainly affect the islands from Kauai to Molokai with increased windward showers through Tuesday, before sliding over to Maui County and the Big Island Tuesday night. Anticipating the details of trade wind cloud and shower coverage at longer forecast times is difficult at best, but additional trade showers are a certainty at times through the upcoming week.
The mid-level portion of a trough aloft over the area will weaken over the next 24 hours or so, leading to increased stability. However, the axis of an upper-level trough, now near Maui, will remain near the islands through the upcoming week. The expectation is that this trough will slide westward, bringing periods of high clouds to islands skies this week, especially over Maui and the Big Island initially. A closed low aloft may develop within the trough to the SW of the islands during the second half of the week, potentially bringing widespread layered clouds to all islands, and a slight increase in instability. Forecast sky cover has been increased over all islands from Wednesday night into Saturday.

Aviation

Moderate to locally breezy trade winds will carry clouds and light showers towards windward slopes and coasts. Isolated MVFR CIG and VIS are to be expected in showers, especially along northeast facing slopes and coasts. Mountain obscuration could become an issue for northeast facing slopes of the Big Island towards morning.
Recent satellite imagery, as of 1 AM Monday, reveals a ragged band of showers along the Big Island Windward Coast. Additional, better defined bands can be seen just upstream of the smaller islands. The next impulse of showers should reach windward Maui and Molokai by morning and the rest of the smaller islands later in the day.
The air mass over the state remains moist and moderately unstable. High topped, locally heavy showers are possible over Big Island summits late this coming afternoon and early evening.
AIRMET Tango remains in effect for low level mechanical turbulence to the lee of higher terrain. Conditions are expected to persist through 24 hours and possibly beyond.

Marine

A high pressure system north of the islands will keep moderate to fresh trade winds in the forecast through the week. Winds will be locally strong in the typical windier waters and channels near Maui and the Big Island. A Small Craft Advisory (SCA) was extended for these windier eastern waters through early Wednesday evening. The SCA was expanded in coverage to include more waters around Kauai and Oahu in the short range SCA issued until this evening. Brief passing showers are forecast through the week for all marine areas.
Small northwest to north swells will continue to generate small surf along most north and west facing shorelines through Tuesday. A larger, longer period northwest swell associated with former Typhoon Malakas will build from Tuesday into Wednesday. This new swell will boost surf along north and west facing shores to head-high or slightly higher lasting into Friday. Another long period northwest swell arrives late Friday into Saturday to near High Surf Advisory levels. Expect elevated surf heights along north and west facing shores to last through the weekend.
South shore surf heights will remain elevated today and then trend lower tonight and Tuesday as the current long period south swell energy begins to decline. The next larger long period south swell will arrive late Friday into Saturday, elevating surf heights along south facing shores just in time for the weekend. East shore surf will remain small and choppy over the next several days.

HFO Watches/Warnings/Advisories

Small Craft Advisory until 6 PM HST Wednesday for Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Leeward Waters, Big Island Southeast Waters.
Small Craft Advisory until 6 PM HST this evening for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Oahu Leeward Waters, Kaiwi Channel.

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Data Courtesy of NOAA.gov